1. Field of the Invention
The present invention relates to a bearing with a rotation sensor in which an optical or a magnetic rotation sensor is incorporated in a bearing and a method of incorporating the above to a rotating object.
2. Description of the Background Art
For example, there is a bearing with a rotation sensor in which a rotation sensor is mounted on a roller bearing to detect a rotation speed or a rotation direction. According to such bearing with the rotation sensor, as disclosed in Japanese Unexamined Patent Publication No. 9-297151, for example, a sensor is arranged at an outer race which is a fixed-side race and a sensor target ring is arranged at an inner race which is a rotation-side race. The sensor target ring comprises a detector at one end face of a flange, which comprises a region in which light is reflected and a region in which light is not reflected which are alternately arranged. A rotation sensor detects the rotation speed or the rotation direction by irradiating the detector with light from the sensor and sensing the reflected light from the detector.
According to the conventional optical bearing with the rotation sensor, the sensor housing comprising the sensor is mounted on the fixed-side race and the sensor target ring is incorporated in the rotation-side race. Therefore, when an outer peripheral surface of a rotation spindle engages with an inner peripheral surface of the rotation-side race to be fixed, when its engaging force is small, a skid is generated between the rotation spindle and the rotation-side race of the bearing comprising the sensor target ring during rotation. Especially, when the bearing with the rotation sensor is incorporated in an office machine such as a copying machine or a printer, engagement of a bearing could be loose and tolerance of size is increased. Thus, it is highly likely that the skid is generated. As a result, rotation displacement of the rotation spindle is not correctly measured and measurement cannot be taken with high precision.
As means for solving the above problem, a method in which the sensor target ring and the rotation-side race are separated and the sensor target ring is directly mounted on the rotation spindle is considered. Thus, even when a skid is generated between the rotation-side race and the rotation spindle, since relative displacement in the rotation direction is not generated between the rotation spindle and the sensor target ring, measurement can be taken with high precision without affecting the rotation detection precision of the rotation spindle.
However, when the sensor target ring and the rotation-side race are separated, it is necessary to handle the bearing and the sensor target ring separately when they are transported before the bearing is mounted on the rotation spindle.